1. Technical Field
The present invention relates to a small-sized and inexpensive semiconductor module of large capacity, in which a semiconductor module unit packaged with a semiconductor device is compactly packaged on a mother substrate.
2. Background Art
It is a recent trend that varieties of electronic equipment and instrument small in size, light in weight and large in capacity have been increasingly demanded, and to meet such a demand, various types of semiconductor modules have been developed.
FIG. 5 is a sectional view showing a construction of a semiconductor module according to one of prior arts. In the drawing, reference numeral 10 is a semiconductor module. This conventional module 10 is arranged in the following manner. First, a semiconductor chip (not illustrated) is joined to a substrate 2, and an electrode thereof and an electrode pad (not illustrated) of a circuit pattern formed on the substrate 2 are conductively connected through a thin metal wire (not illustrated). Then, they are sealed together with a semiconductor chip portion 1 with a resin. Bump electrode 3 for a CSP (chip size package) type semiconductor device 4 are conductively connected to required electrode pads 5a of the circuit pattern formed on upper and lower faces of a unit substrate 5. The bump electrodes 3 serve as an external terminal disposed on the lower face of the substrate 2 conductively connected to the mentioned circuit pattern. Thus, a semiconductor unit module 6 is formed. Further, an electrode pad 5b conducting to the electrode pad 5a is conductively connected to electrode pads 7a of the circuit pattern formed on upper and lower faces of a mother substrate 7 through connecting bumps 8. Thus, a conventional semiconductor module 10 is obtained.
In the semiconductor module 10 of above construction, for the arrangement of the connecting bumps 8, it is required to specially prepare welding balls of large diameter (not smaller than about 1.5 mm in xcfx86) exceeding normal diameter (normally 0.5 to 0. 8 mm in xcfx86) for each semiconductor module 10 in conformity with thickness of the CSP type semiconductor device 4, which eventually results in a high manufacturing cost. Note that, generally, number of the bump electrodes 3 serving as external terminal is same as that of the connecting bumps 8. The CSP type semiconductor device 4 is usually applied to a semiconductor module having not less than 60 pins. Therefore, when diameter of the welding balls for the connecting balls 8 is large, the unit substrate 5 is obliged to be large-sized in view of designing the wiring pattern on the unit substrate 5. In the worst case, there is a possibility that size of the unit substrate 5 is equivalent to or larger than that of the mother substrate 7. In such a case, there remains no space enough to package other circuit components (such as capacitor, resistor) on the mother substrate 7, and it becomes impossible to arrange a semiconductor module. Thus, a problem exists in that it is inevitable for the mother substrate 7 to be further large-sized.
The present invention was made to solve the above-discussed problems and has an object of providing an inexpensive semiconductor module of large capacity capable of being formed into a small-sized.semiconductor module without using any special assembling component irrespective of thickness of a semiconductor device to be packaged therein.
To accomplish the foregoing object, a semiconductor module according to the invention comprises: a semiconductor module unit in which external terminals of semiconductor devices are packaged in electrode pads of a unit substrate on upper and lower faces of which electrode pads of a circuit pattern are disposed; a mother substrate on upper and lower faces of which electrode pads of the circuit pattern are packaged and which is provided with.either concave portions or through holes, each having a depth enough to insert each semiconductor device of the semiconductor module unit disposed on upper and lower faces of the mentioned electrode pads; and a first conductive connector for conductively connecting the electrode pads of the unit substrate conducting to the electrode pads packaged with the external terminals of the semiconductor devices and the electrode.pads of the mother substrate.
As a result of such construction, diameter of the first conductive connector can be small-sized, and a small-sized semiconductor module can be obtained.
It is preferable that the unit substrate of the mentioned semiconductor module is comprised of a main substrate on upper and lower faces of which the electrode pads of the circuit pattern packaged with the external terminals of the semiconductor devices are disposed, and a spacer forming a concave portion having a depth enough to surround the semiconductor devices disposed on one face of the mentioned main substrate and packaged in the mentioned one face; in which the main substrate and the spacer are provided with through holes conducting to the electrode pads and of which upper and lower ends are exposed; and plural semiconductor module units provided with said unit substrate and the semiconductor devices, packaged in the mentioned unit substrate are disposed in such a manner as to be stacked in order under the condition that the semiconductor devices of the other semiconductor module units are inserted in the concave portion of the unit substrate so that through holes of each semiconductor module unit are conductively connected to one another through a second conductive connector.
As a result of such construction, a small-sized semiconductor module of a larger capacity can be obtained.
It is also preferable that the depth of the concave portion or the through holes of the mother substrate is established to be a depth in which the semiconductor devices inserted in the concave portions or the through holes of the mother substrate are disposed back to back with a space between each semiconductor device and a bottom face of each concave portion of the mother substrate or with a space between the semiconductor devices..
It is also preferable that the depth of the concave portion of the unit substrate of the semiconductor module unit is established to be a depth in which one semiconductor device inserted in the concave portions of the unit substrate of one semiconductor module unit is disposed back to back with another semiconductor device of another semiconductor module unit with a space between the semiconductor devices.
Another semiconductor module according to the invention comprises: plural semiconductor module units in which external terminals of semiconductor devices are packaged in electrode pads of a unit substrate on upper and lower faces of which electrode pads of a circuit pattern are disposed; a mother substrate on upper and lower faces of which electrode pads of the circuit pattern is disposed and the mentioned plural semiconductor module units are vertically disposed; and a conductive connector for conductively connecting the electrode pads of the unit substrate conducting to the electrode pads packaged with the external terminals of the semiconductor devices and the electrode pads of the mother substrate.
As a result of such construction, a small-sized semiconductor module of a larger capacity can be obtained.
It is also preferable that the semiconductor devices of the semiconductor module are CSP type semiconductor devices.